Shared data with relationship information

ABSTRACT

To enable a shared model comprising shared plans having a hierarchy with two or more levels, a data item stored in a shared plan is provided with relationship information indicating whether or not there is a previous data item in the shared plan, whether or not there is a next data item in the shared plan, and whether or not the data item has a relationship to a data item in a higher level plan.

RELATED APPLICATION

This application claims priority to FI application no. 20125700 filedJun. 21, 2012 and to U.S. provisional application No. 61/663,765, filedJun. 25, 2012, both of which are assigned to the applicant of thepresent application and are incorporated herein by reference in theirentirety for all purposes.

FIELD

The invention relates to data processing, and particularly torelationship information indicating how a data item relates to otherdata items in shared data.

BACKGROUND ART

The following description of background art may include insights,discoveries, understandings or disclosures, or associations togetherwith disclosures not known to the relevant art prior to the presentinvention but provided by the invention. Some such contributions of theinvention may be specifically pointed out below, whereas other suchcontributions of the invention will be apparent from their context.

Computer based structured storage systems, such as computer file systemsand database systems, have been remarkably successful at providing userswith quick and facile access to enormous amounts of data. At the sametime data management systems have been evolved for handling shared orconcurrent access and update of data in a server by different clients.Evolvement of cloud computing has also introduced different data-sharingservices.

The development of data processing systems, computers and computerapplications has transformed different processes into computerizedprocesses. One example of such a process is modeling. Modeling meansthat a model is created from a product under design for describing theproduct to be constructed, the model containing at least informationneeded to illustrate the product. For example, a product model of abuilding is an entity consisting of the product data on the life span ofthe building and building process.

To provide dynamic environment and concurrent modeling for the productmodel utilizing shared data, a mechanism to handle differentalternatives and phases of modeling, for example, is needed.

SUMMARY

The invention relates to methods, an apparatus, a computer pro-gramproduct and a system which are characterized by what is stated in theindependent claims. Preferred embodiments are disclosed in the dependentclaims.

An aspect provides relationship information indicating relations a dataitem in a shared memory has to other data items in the shared memory.

An advantage of the relationship information is that it provides amechanism to handle different alternatives and phases of modeling.Further, by means of the relationship information, shared plans having ahierarchy with two or more levels may be created and maintained.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, different embodiments will be described in greaterdetail with reference to the attached drawings, in which

FIG. 1 is a simplified block diagram illustrating a system used as anexample;

FIG. 2 illustrates packet relationship information;

FIG. 3 illustrates tracking information; and

FIGS. 4 to 14 are flow charts illustrating different exemplaryfunctionalities.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

Exemplary embodiments of the present invention will now be de-scribedmore fully hereinafter with reference to the accompanying drawings, inwhich some, but not all, embodiments of the invention are shown. Indeed,the invention may be embodied in many different forms and should not beconstrued as limited to the embodiments set forth herein; rather, theseembodiments are provided so that this disclosure will satisfy applicablelegal requirements. Although the specification may refer to “an”, “one”,or “some” embodiment(s) in several locations, this does not necessarilymean that each such reference is to the same embodiment(s), or that thefeature only applies to a single embodiment. Single features ofdifferent embodiments may also be combined to provide other embodiments.

The present invention is applicable to any application and/or processsupporting use of shared data, any computing apparatus and correspondingcomponent(s) configured to create and/or access and/or update/modifyshared data stored on a shared data repository (memory), in any datastorage system or any combination of different data storage systems,such as data repositories (memories) in a client-server structure. Thedata repository may be an external data repository shared by differentuser apparatuses, and/or the data repository may be an internal memoryof a computing apparatus shared by different applications or differentapplication instances. The methods and processes used by theapplications, by the computing apparatuses, by different data managingsystems, including file systems, and data repositories, are developing.Such development may require extra changes to an embodiment. Therefore,all words and expressions should be interpreted broadly and they areintended to illustrate, not to restrict, the embodiment.

In the following, different embodiments will be described using, as anexample of a system architecture whereto the embodiments may be applied,an architecture based on a client-server structure and data sharingbased on a “copy—modify locally” solution, without restricting theembodiments to such an architecture, however. It should be appreciatedthat herein the client-server structure also covers applications and/orapplication instances acting as the client and the common memory withits control system performing the server functionality required for thatspecific implementation.

Further, in the following modeling is used as an example of a processutilizing shared data and a model is used as an example of a modelingentity. Examples of such entities include a building with relatedinformation, a budget of a company having many subsidiaries, a car withspecific design and manufacturing details.

A general architecture according to an embodiment is illustrated inFIG. 1. FIG. 1 is a highly simplified system architecture only showingsome elements, networks and functional entities, all being logical unitswhose implementation may differ from what is shown. The connectionsshown in FIG. 1 are examples of logical connections; the actual physicalconnections may be different. It is apparent to a person skilled in theart that the systems also comprise other functions and structures. Itshould be appreciated that the functions, structures, elements and theprotocols used in or for data accessing, updating and management areirrelevant to the actual invention. Therefore, they need not bediscussed in more detail here.

The system 100 illustrated in FIG. 1 comprises one or more apparatuses120 (only one shown in FIG. 1), connected to a server system 110. Theconnection may be a direct connection over Bluetooth or a cable or viaan USB port, for example, or a connection over a network, such as amobile network, a public switched telephone network, a wide area networkWAN, Internet, a local area network LAN open for all users or withrestricted access (an enterprise LAN or office LAN, for example), or aprivate network.

In the example of FIG. 1, the server system 110 comprises a datarepository (not illustrated separately in FIG. 1) managed by a filemanagement system or a database management system, for example, andwhich is accessible by means of apparatuses 120 providing user accountshaving proper access rights, for example. The management system storescontents, allowing data creation, deletion, update, maintenance andsearch, and may provide access, security, backup and other facilities,such as monitoring modifications to data and downloading modificationsto relevant clients (or applications or application instances in clientapparatuses).

The server system 110 may be one server node, or a correspondingcomputing apparatus, comprising a processor(s) and memory for managementsystems and for a data repository, or different modules and/or memory ofthe server system may be implemented in two or more physical or logicalentities. For example, the data repository and the server system 110 maybe distributed between two or more of the clients. The server system 110may even be an internal system within a computing apparatus, forexample, when data sharing is between applications that run on thecomputing apparatus.

The data repository may be any kind of conventional or future datarepository, including distributed and centralized data storages (datawarehousing), managed by any suitable management system. An example of adistributed data warehousing includes a cloud storage in a cloudenvironment (which may be a public cloud, a community cloud, a privatecloud, or a hybrid cloud, for example). The implementation of the datarepository and the way in which the shared data is stored and updatedbear no significance to the invention and need not be described indetail here.

In the illustrated example, at an imaginary modeling phase, the datarepository contains for a model different plans 111, 112, 113, 114, 115,116, each plan comprising one or more data items that form the shareddata of the plan in question and that are arranged to be in anunambiguous sequence (order). It should be appreciated that herein a“sequence” means the particular order in which events or actionshappened, and the unambiguous sequence indicates astoring/saving/publishing order in the data repository. Herein a dataitem means a set of logically related data treated as a unit. It shouldbe appreciated that what may constitute a data item depends on theapplication used. However, the data item itself, or information storedtherein, bears no significance; the invention may be utilized with anykind of data and file format, etc., as long as the data is associatedwith relationship information described in more detail below. Further,shared data means herein data that is at least accessible, preferablyalso modifiable, by different users (by means of user apparatuses)and/or different applications and/or different application instances.

In the illustrated example, a plan 111 is a master plan. Herein, themaster plan means a plan which is on the highest level i.e. does notrefer to any other plan. The master plan may be called highest plan,highest level plan, supreme plan, or upmost plan, for example.

In the illustrated example, the other plans, i.e. plan A 112, plan B113, plan C 114, plan D 115 and plan Bb 116, may be parallel oralternative plans. A parallel plan means that it is intended to be savedin the master plan (or in the higher level plan) when it is ready forstoring. An alternative plan means that one of the plans that arealternative to each other, is selected to be saved in the master plan(or in the higher level plan) while the other(s) is/are not. The“leftover” plans may be deleted from the data repository or marked assuch to ensure that no one uses them in further modeling. For example,plan A 112 may be alternative to plan B 113. As can be seen from theillustrated example, a plan level of plans A 112, B 113 and D 115 is onelevel lower than the master plan, i.e. the master plan is a higher levelfor them. Further, plan A 112 is a higher level plan for plan C 114, andplan B is a higher level plan for plan Bb 116. Depending on animplementation, information on a plan type (master, parallel,alternative) may or may not be maintained in the system. Further, otherplan types may be introduced, and the invention may be implementedwithout any plan type.

In the illustrated example, at the imaginary modeling phase, plan D 115is the only plan wherefrom data is stored back in the higher level plan(in the master plan 111).

As to building information modeling (BIM), the shared model comprisingdifferent plans may be a building information model in a multiuserenvironment. BIM is a digital representation of the building process tofacilitate exchange and interoperability of information in digitalformat. For example, the information may relate to different phases ofbuilding process, and/or to different detailed information, like modelsof beams, columns, plates, connections between beams and columns, orconnections between beams and plates, drawings, a list of elementsneeded for a building, etc. A plan M may illustrate a building that iscurrently being planned (a building intended to be built), a plan A maybe a concrete frame plan for the building, a plan B a steel structureframe for the building, a plan Bb1 a plan for stiffening the steelstructure frame, the plan C concrete partition wall plan, and the plan Da foundation plan for the building, or the plan A may be a plan of acontractor taking care of building the frame, the plan B may be a planof a head structural engineer, the plan Bb1 may be a plan of anelectronic designer, the plan C may be a plan of a prefabricationfactory, and the plan D may relate to municipal engineering. Further,all plans may be shared plans of one party, for example the headstructural engineer may have several engineers or subcontractorsproviding the shared plans, and the master plan may then be sharedupwards as a plan to a building information model shared by differentparties. It should be appreciated that file format(s) of the data itemsbear(s) no significance and any means to obtain data exchange betweendifferent applications may be used, if necessary.

To keep track of the level relationships and data item relationships,each data item stored in the shared memory contains or is associatedwith data item relationship information described in more detail withFIG. 2. For example, if the data item is a packet, the data itemrelationship information may be included in a header. By means of thedata item relationship, the data items stored in the shared memory maybe logically organized into plans as is shown in FIG. 1, the linesbetween different data items illustrating the relationship informationof a corresponding data item.

In the illustrated example, the data repository also contains hierarchyinformation 117 for the model. The hierarchy information may be a tablecontaining for example a name of each plan, and a name of a higher leverplan and a name(s) of a lower level plan(s), if a plan has such. Thehierarchy information may also contain some other information, like atype of a plan, its purpose, etc. The hierarchy information may also beused to keep track of shared tracking information, for example bystoring information on users, what they have loaded, the last loadeddata item, the last stored data item, etc. Further, the hierarchyinformation, or part of it, may be visible or non-visible to users, orto some users. It should be appreciated that hierarchy information isadditional information and embodiments may be implemented without suchhierarchy information.

Below, the term “shared plan” means a plan stored in the data repositoryfor the model, and “shared model” means the modeling entity formed byall shared plans belonging to one model. It should be appreciated thatthe data repository may comprise several shared models, although onlyone is illustrated in FIG. 1. Further, it should be appreciated thatherein it is assumed, for the sake of clarity, that all users see thesame shared model and are allowed to use the same model and a logicalmemory structure in which there is a local memory and a shared memory,without restricting the examples and implementations to such a solution.

The apparatus 120 may be any computing apparatus with which shared datacan be accessed, created, obtained/retrieved/downloaded, modified,deleted, updated and/or published. Examples of apparatuses include auser terminal or work station, such as a laptop, a smartphone, apersonal computer, a tablet computer, a field device, an e-readingdevice, a printer with processing capabilities, or a personal digitalassistant (PDA).

The apparatus 120 is configured to perform one or more functionalitiesdescribed below with an embodiment, and it may be configured to performfunctionalities from different embodiments. For this purpose, theapparatus 120 comprises a plan managing unit (PMU) 125, and at least onememory 121 for storing a working version (a working copy) of each of oneor more plans the user has selected to create or modify or view, forexample as a “run-time database”.

In the illustrated example, the user has selected to modify the plan Bb1and therefore the memory comprises a local version 122 of the plan Bb1,the local version comprising a snapshot 123 of the plan Bb1. Thesnapshot comprises copies of data items belonging to the plan Bb1 in thedata repository up to and including the data item the user has selectedbut not those after the selected data item, as will be described in moredetail later. The local version 122 further comprises trackinginformation 124 for the plan, the tracking information being describedin more detail with FIG. 3. Naturally, the local version comprisesmodifications the user has made to the loaded plan, but they are notillustrated in FIG. 1.

Although the memory 121 is illustrated as a memory separate from thememory in the server, it should be appreciated that the memory may belocated anywhere; it will suffice that it is the memory comprising aworking copy and used by the client, or at the plan managing unit (PMU)125 as the memory 121.

The apparatus 120, or a corresponding component, is a computing devicecomprising not only prior art means, but also means for implementing aplan managing unit functionality described with an embodiment, and itmay comprise separate means for each separate function, or means may beconfigured to perform two or more functions, and even to combinefunctions of different embodiments. These means may be implemented byvarious techniques. For example, the means may be implemented byhardware (one or more apparatuses), firmware (one or more apparatuses),software (one or more modules), or combinations thereof. For firmware orsoftware, implementation can be through units/modules (e.g. procedures,functions, and so on) that perform the functions described herein.

The apparatus also comprises different interface units, like a userinterface by means of which a user can create data, modify and/or updatedata, study it, print data (such as drawings or reports), etc. Inaddition, the apparatus may comprise a separate interface unit includinga transmitter and/or a receiver or a corresponding means for receivingand/or transmitting information.

Each of the units may be a separate unit or integrated into anotherunit, or the units may be integrated together. It should be appreciatedthat the apparatus may comprise other units used in or for dataprocessing, like a change management unit(s). However, they areirrelevant to the actual invention and, therefore, they need not bediscussed in more detail here.

The apparatus and corresponding components implementing a functionalityor some functionalities according to an embodiment may generally includea processor (not shown in FIG. 1), controller, control unit,micro-controller, or the like connected to a memory and to variousinterfaces of the apparatus. Generally the processor is a centralprocessing unit, but the processor may be an additional operationprocessor. The plan managing unit 125 may be configured as a computer ora processor, or a microprocessor, such as a single-chip computerelement, or as a chipset, including at least a memory for providingstorage area used for arithmetic operation and an operation processorfor executing the arithmetic operation. The plan managing unit 125 maycomprise one or more computer processors, application-specificintegrated circuits (ASIC), digital signal processors (DSP), digitalsignal processing devices (DSPD), programmable logic devices (PLD),field-programmable gate arrays (FPGA), and/or other hardware componentsthat have been programmed to carry out one or more functions of one ormore embodiments. An embodiment provides a computer program embodied onany client-readable distribution/data storage medium or memory unit(s)or article(s) of manufacture, comprising program instructions executableby one or more processors/computers, which instructions, when loadedinto an apparatus, constitute the plan managing unit 125. Programs, alsocalled program products, including software routines, program snippetsconstituting “program libraries”, applets and macros, can be stored inany medium and may be downloaded into an apparatus. The data storagemedium or the memory unit may be implemented within theprocessor/computer or external to the processor/computer, in which caseit can be communicatively coupled to the processor/computer via variousmeans, as is known in the art.

As said above, the client includes memory 121 for acting as a “run-timedatabase”, for example. The memory may be volatile and/or non-volatilememory and it may also store other data. For example, the memory maystore a computer program code such as software applications (forexample, for the editing unit or the data publishing unit) or operatingsystems, information, data, content, or the like for the processor toperform steps associated with operation of the client in accordance withembodiments. The memory may be, for example, a random access memory, adouble floating-gate field effect transistor, a hard drive, anotherfixed data memory or storage device or any combination thereof. Further,the memory, or part of it, may be a removable memory detachablyconnected to the client.

Although the apparatus has been depicted as one unity, differentprocessors, controllers, interfaces and/or memory/memories may beimplemented in one or more physical or logical units.

Below, different examples are described assuming that the data itemsstored in the data repository are identified by means of globally uniqueidentifiers (GUIDs) without restricting the examples to such anidentification method. A GUID is a special type of identifier known byone skilled in the art and used in software applications to provide aunique reference number or reference time.

FIG. 2 illustrates an example of relationship information 200 that adata item stored in the data repository (i.e. in a shared plan) maycontain. The data item A3 in plan A illustrated in FIG. 1 is used as anexample. The relationship information 200 comprises a GUID 201identifying the data item in question. The relationship information 200further comprises information on a previous data item 202 and on a nextdata item 203 and information on a higher level relationship (hlr) 204and higher level action performed (hlr-act) 205. If the value field ofthe next data item 203 indicates no association with another data item,for example is empty or has “no”, this implies that the data item is thelast one stored to this plan. If the value field of the previous dataitem 202 is empty or has “no”, this implies in the example that the dataitem is the first one that is specific in this plan. In the example, thevalue field of the higher level relationship 204 either contains a GUIDidentifying the higher level data item or is empty/has “no”, and thevalue field of the higher level action 205 contains information on theperformed action for which the relationship was used with this data itemor is empty/has “no”. In some other examples, the value field of theprevious data item 202 may contain the GUID identifying the higher leveldata item and the higher level relationship 204 contains the (last)performed action, or the fields 204 and 205 are combined so that thevalue field is either empty/has “no” or contains the GUID identifyingthe higher level data item and information on the last performed action.Examples of actions are described in more detail with FIG. 4.

Other examples of the content(s) of the packet relationship informationusing the plans illustrated in FIG. 1 include:

-   -   data item A1 contains its GUID A1, the value field of the        previous data item is empty, the value field of the next data        item is associated with A2, and the value field of the higher        level relationship contains M2 and “load”,    -   data item D2 contains its GUID D2, the value field of the        previous data item contains D1 and the value field of the next        data item has no association, and the higher level data item        relationship information contains M3 and “save to higher”,    -   data item A5 contains its GUID A5, the value field of the        previous data item is A4, and the value fields of the next data        item and the higher level relationships are empty.

In one implementation, the packet relationship may further comprise afield “plan GUID”, the value of which contains a start packet of theplan, and hereby indicates the name and/or other identificationinformation on the plan.

It should be appreciated that instead of, or in addition to, the higherlevel data item relationship, a lower level data item relationship maybe used to indicate the hierarchy.

As is evident from the above, the plan hierarchy may be formed by merelyusing the relationship information, since by means of the relationshipinformation each data item indicates to other data items how it connectsto the hierarchy.

FIG. 3 illustrates tracking information 300 maintainedclient-specifically for a local version of a plan. Typically it ismaintained in a run-time database of the client and by the client.However, it should be appreciated that the tracking information may bemaintained anywhere where the client may access it, and by an entityother than the client, for example by a server. The illustratedimaginary phase in FIG. 1 is used as an example. The trackinginformation 300 comprises at least a field herein called a current 301,and in the illustrated example it further comprises following auxiliaryfields: higher level current (hl-cur) 302, and last higher level action(l-hl-act) 303. The value field of the current 301 contains the GUIDidentifying the data item which is the last one loaded to or saved fromthe local memory from the shared plan in the local version of the plan.The value field for the higher level current 302 contains the GUIDidentifying a data item in a higher level shared plan of the sharedplan, which data item is the last higher level data item referred to bya data item in the shared plan at the point of the snapshot, and thevalue field for the last higher level action 303 indicates the lastperformed action between the shared plan and the higher level sharedplan. The value fields for the higher level current 302 and the lasthigher level action 303 may be empty if the plan loaded to the localmemory is the master plan. Further, instead of having the auxiliaryfields, corresponding information may be obtained by searching referenceinformation stored in the shared plan starting from the data itemreferred to by the GUID.

Other examples of the content(s) of the exemplary tracking informationusing the plans illustrated in FIG. 1 include:

-   -   for a snapshot taken from data item C1 in plan C:        -   current: C1        -   higher level current: A3        -   higher level action: load    -   for a snapshot taken from data item A5 in plan A:        -   current: A1        -   higher level current: M2        -   higher level action: load    -   for a snapshot taken from data item D2 in plan D:        -   current: D2        -   higher level current: M3        -   higher level action: save

FIG. 4 is a flow chart illustrating a functionality of an apparatus, ormore precisely, a plan managing unit according to an exemplaryembodiment. In the illustrated examples, following assumptions are madefor the sake of clarity, without restricting solutions to suchassumptions:

-   -   a packet is used as an example of a data item;    -   a packet contains only modifications (changes);    -   a plan starts with an empty packet having only relationship        information, below called packet relationship information, other        packets contain changes as contents; and    -   loading from or saving in the shared plan or higher level shared        plan will succeed.

Although following examples are described using shared data in whichonly changes are published (stored), the change management, includingconflict handling, is not described in detail herein. Any changemanagement may be used.

An example of change management that may be used is based on a principleof causality and dualistic sequence information. The principle ofcausality is the relationship between a cause and an effect, where theeffect is a consequence of the cause and happens after the cause. Thedualistic sequence information includes an unambiguous sequence andinformation indicating a possible internal (local) deviation from theunambiguous sequence, and it is also stored in the shared data. Thedualistic sequence, created with (during, by) creating, editing,updating etc. the model locally, indicates that there may be a localdeviation from a global sequence by means of the deviation information,and therefore the deviation is detectable later. In the concept, ifduring processing of a local copy of the shared data, a change to theshared data is published by another user and when the change is loadedto the local copy, a local deviation is created, and when the result ofthe processing (i.e. unpublished changes) is published, it is associatedwith an unambiguous sequence reference and the local deviation. Thechange management is described in more detail in Finnish patentapplication 20125270, corresponding EP application no. 12 159 577.1, andcorresponding U.S. patent application Ser. No. 13/421,896, assigned tothe applicant, which are hereby incorporated by reference. Further, theprinciple of causality and the dualistic sequence information are alsoimplemented in Tekla® Structures release 17.1, released in October 2011.It should be appreciated that the dualistic sequence information, withor without the causality principle, may also be used for conflictmanagement detected when data items are loaded from the shared plan orfrom the higher level shared plan. Further, it should be appreciatedthat the details of updating a snapshot of a plan and related actionsare known by one skilled in the art, and therefore they are notdescribed herein.

One way to ensure that the saving will succeed is to use an atomictransaction that ensures that all that is supposed to be stored in ashared plan or in a higher level shared plan, like a packet withcorresponding relationship information, below called packet relationshipinformation, or two or more packets with the information, are stored inthe data repository or none of them. However, any other means may beused.

Further, instead of saving almost immediately after a start packet isformed the start packet as an empty packet in the shared plan, the startpacket may be stored later (at a later stage) and with actual contents.A modification of this kind to the examples described herein isstraightforward to one skilled in the art, and therefore it is notdescribed in detail herein.

Referring to FIG. 4, it is detected, in step 401, that the user hasselected a certain packet in a shared model, i.e. a packet in one of oneor more plans in the data repository, to be loaded to the local memoryto create a local version of the plan. The plan may be any plan, and theuser may select any packet belonging to the plan, i.e. the packet may bethe newest one or an older one. Because of the selection, trackinginformation is created in step 402. When the tracking information iscreated, a value field of the current is set to be the GUID of thepacket the user selected, and the value fields relating to the higherlevel are set according to the situation of the packet the user selected(see above).

Then it is checked, in step 403, whether the user selected an action“create a new plan”. If the user did not select “create a new plan”(step 403), a primary load is performed in step 404. The primary loadmeans that packets that represent the plan at the selected point areloaded (i.e. copied) to the local memory, and a snapshot is created. Forexample, the snapshot in FIG. 1 illustrates which packets are loaded tothe local memory when the user has selected the packet Bb1 in the planB. Another example for a snapshot is that the plan A has the packets A1to A5 and a user wants to create the plan C that comprises the packetsA1 to A3 from the plan A. When the user takes a snapshot from the packetA3, the packets A4 and A5 are not loaded in the primary load to be partof the plan C.

Then the modeling is monitored in step 405, and in the illustratedexample the plan managing unit is configured to react to certain userinputs, i.e. actions (or commands). In the illustrated example, theactions are “load”, “save”, “save as a new plan”, “load from higherlevel”, “save to higher level” and “exit”. The action “load” means thatupdates to the shared plan, a copy of which is processed, are obtained.The action “save” means that the modifications made to the snapshot areto be saved in the shared plan. The action “save as a new plan” meansthat the modifications to the snapshot are not to be saved in the sharedplan, although that was the intention earlier (and the reason why“create new” was not selected in the beginning). The action “load higherlevel” means that updates to the higher level shared plan are obtained.The action “save to higher level” means that the modifications made tothe snapshot, as well as modifications in the plan not yet saved in thehigher level plan are to be saved in the higher level shared plan. Theactions “save”, “load”, “save to higher level”, “load from higher level”may be interpreted as hierarchy rules according to which modeling datamay be loaded from a master plan to other plans in the hierarchicalstructure, and modeling data saved in the master plan from the otherplans in the hierarchical structure.

If action “load” is detected (step 406), the steps of FIG. 5 areperformed in step 407, and the monitoring is continued (step 405).

If action “save” is detected (step 408), the steps of FIG. 6 areperformed in step 409, and the monitoring is continued (step 405).

If action “save as a new plan” is detected (step 410), the steps of FIG.7 are performed in step 411, and the monitoring is continued (step 405).

If action “load from higher level” is detected (step 412), the steps ofFIG. 7 are performed in step 413, and the monitoring is continued (step405).

If action “save to higher level” is detected (step 414), the steps ofFIG. 8 are performed in step 415, and the monitoring is continued (step405).

If action “exit” is detected (step 416), the process exits in step 417.In one implementation, the process may check before exiting whether theprevious action related to a save action, i.e. whether it was “save” instep 408 or “save as a new plan” in step 410 or “save to higher level”in step 414, and if the previous action did not relate to the saveaction, the process exits by storing the modifications and otherinformation in the local memory, and when the user continues with theplan, the local copy is processed as if it had not been stored, at leastfrom the point of view of the shared plan.

If action “create new” is detected (step 403), the steps of FIG. 10 areperformed in step 418, and then it is checked whether or not the usercontinues (step 419) to edit the model. If the user continues, theprocess proceeds to step 404 to perform the primary load, otherwise theprocess exists (step 417).

It should be appreciated that although in the illustrated example theprimary load is performed automatically, this need not be the case; theprimary load may be provided as a separate action or when an action“load” is performed for the first time for the plan.

FIG. 5 illustrates an example of steps performed in response to “load”action.

When the user has selected “load”, the GUID of the current is obtainedfrom the tracking information in step 501, and a packet having the GUIDis searched for in step 502 from the shared plan. In the illustratedexample it is assumed that such a packet is found. Then it is checked instep 503 from the packet relationship information of the found packetwhether or not the value field of the next packet indicates that a nextpacket exists. If the value field is associated with a GUID, the nextpacket(s) is/are loaded in step 504 as long as there are next packets tobe loaded. In other words, the packet last loaded is a packet whosevalue field of the next packet is not associated with a GUID. Then thevalue field of current in the tracking information is updated to be theGUID of the packet last loaded. Then the process returns to FIG. 4.

If in step 503 it is detected that there exists no next packet, thereare no new packets to be loaded and the process returns to FIG. 4.

It should be appreciated that after a packet has been loaded to thelocal copy, or after loading of packets ends, the packet(s) may undergoa change management/conflict handling procedure, for example the changemanagement based on the principle of causality and dualistic sequenceinformation described above. However that need not be described in moredetail here.

FIG. 6 illustrates an example of steps performed in response to “save”action.

When the user has selected “save”, the GUID of the current is obtainedfrom the tracking information in step 601, and a packet in thecorresponding plan in the data repository, i.e. the shared plan, havingthe GUID of the current is searched for in step 602. In the illustratedexample it is assumed that such a packet is found. Then it is checked instep 603 from the packet relationship information of the found packet,whether or not the value field of the next packet indicates that a nextpacket exists.

If the value field of the next packet is associated with a GUID (step603), in the illustrated example the user is prompted in step 604whether to load one or more packets and perform the save or to create anew plan. If the user selects to load (step 604), the next packet(s)is/are loaded in step 606 as long as there are next packets to beloaded. In other words, the packet last loaded is a packet whose valuefield of the next packet is not associated with a GUID.

After the packets are loaded, or if the value field of next packet isnot associated with a GUID, a new GUID is obtained and a new packet isformed in step 607, the packet containing modifications made to the planafter the packet indicated by the value field of the current (so called“current packet”) was formed, including loaded information andinformation that may have been stored locally in a local packet formedlater than the “current packet”. The packet relationship information ofthe packet formed in step 607 contains as the previous packet the GUIDof the last loaded packet. It should be appreciated that the actualcontent of the packet, i.e. information other than the packetrelationship information described with FIG. 2, is typicallydetermined/formed by an editing unit and/or a change managing unit,rather than by the packet managing unit, without restricting the exampleto such a solution.

When the packet is ready, it is checked in step 608 from the packetrelationship information of the last loaded packet, whether or not thevalue field of the next packet indicates that a next packet exists. Inother words, it is checked whether or not during the packet forming oneor more packets have been stored in the shared plan. If the value fieldof the next packet is associated with a GUID (step 608), the processproceeds back to step 604 to prompt the user.

If the value field of the next packet is empty (step 608), the packetformed in step 607 is saved in step 609 in the shared plan in the datarepository, and the packet relationship information of the last loadedpacket in step 606 is updated so that the value field of next packet isassociated with the GUID of the formed and saved packet. The trackinginformation is updated in step 610 to have the GUID of the formed andsaved packet as the value of the current, and the process returns toFIG. 4.

If the user selected not to load (step 605), the process proceeds toFIG. 7 to perform the “save as a new plan” action.

In another example, the process may create in step 611 the plan data,and after that proceed directly to step 707 in FIG. 7. The created plandata comprises as a name for the plan the name of the “original” planadded with temporary and creation time, like temporary-A-dd-mm-yy-hh-mm,an indication that it is a parallel plan, and possible additionalinformation, like the purpose of this version (temporary).

In a still further example, if the value field of the next packet isassociated with a GUID (step 603 or step 608), the process is configuredto automatically create a new plan instead of loading. In the example,after step 603 or after step 608 the process proceeds either to step 607or to step 611.

In a yet another example, the process is configured to automaticallycreate a new plan instead of loading only after the packet has beenformed and the value field of the next packet is associated with a GUID(step 608), i.e. steps 604, 605, 606 and 607 are not omitted after step603.

In an implementation in which the shared memory is locked to be used bythe client when the packet indicated as current is found (step 602) orjust before the loading starts, steps 604, 605, 608 and 611 may beomitted. Alternatively, only step 608 may be omitted thereby allowingthe user to determine whether or not to perform the load.

FIG. 7 illustrates an example of steps performed in response to “save asa new plan” action.

When the user has selected “save as a new plan”, the user is promptedfor plan data in step 701, and the plan data is received in step 702.Then the name of the plan is compared, in step 703, with the names in ahierarchy information table in the data repository to minimize a dangerof confusion with several users sharing the model, or part of the model.If the intended name is the same as a name already used (step 704), theuser is prompted in step 705 to input a new name. When the new name isreceived in step 706, the process continues to step 703 to compare thenew name with the names in the hierarchy information.

When the name is not a previously used name, a start packet for the planis formed in step 707 and, in the illustrated example, also a nextpacket for the plan. It should be appreciated that if the “save as a newplan” functionality is triggered from the “save” action described abovewith FIG. 7, and a packet has been already formed, there is no need toform the same packet once again, the already formed packet may be usedas the next packet or its content as a content in the start packet. Thepacket relationship information of the start packet contains in thevalue field of the previous packet no information or “none” and thevalue field of the next packet has no association; the GUID of theselected packet used for snapshot in step 401 in FIG. 4 is added to thefield value of the higher level relationship, and “load” is added to thevalue field of the higher level action. Further, two new GUIDs areobtained in step 707, one for the start packet and the other for thenext packet. The value field of the next packet in the packetrelationship information of the start packet is associated with the GUIDof the next packet. The packet relationship information of the nextpacket contains in the field value of the previous packet the GUID ofthe start packet, the other field values are empty. Further, content isadded to the next packet, so that modifications made to the plan afterprimary load are included into the next packet and, depending on animplementation, also the information obtained during primary load may ormay not be included in the packet.

Then the packets are saved in step 708 to be a new shared plan of theshared model in the data repository, and the hierarchy information isupdated in step 709 to contain required information on the new plan,such as the name of this new plan, the name of the higher level plan ofthis new plan, adding this new plan as a new lower level plan to thehigher level plan, etc. Further, tracking information is updated in step710 to be the tracking information for this new plan. During the updatein step 710, the GUID in the current field is moved to the value fieldof the higher level current, and the GUID obtained in step 707 for thenext packet is set to be the value of the current, and the last higherlevel action is set to be the load. Then the process returns to FIG. 4,and continues monitoring this new plan.

FIG. 8 illustrates an example of steps performed in response to “loadfrom higher level plan” action.

When the user has selected “load from higher level plan”, the GUID ofthe current is obtained from the tracking information in step 801, and apacket having the GUID is searched for in step 802 from the shared plan.In the illustrated example, it is assumed that such a packet is found.Then it is checked, in step 803, from the packet relationshipinformation of the packet found in the shared plan whether the valuefield of the higher level relation contains a GUID or is “no” (orempty). If the packet has no higher level relation (i.e. the value fieldof higher level relations is empty or “no”), it is checked in step 804from the packet relationship information of the packet found in step 802in the shared plan whether or not the value field of the previous packetindicates that a previous packet exists in the shared plan. If the valuefield contains a GUID, there is a previous packet in the shared plan andpacket relationship information of the previous packet in the sharedplan is obtained in step 805 and the process proceeds to step 803 tocheck the higher level relationship of the previous packet.

If in step 804 it is detected that no previous packet exists in theshared plan, there is no higher level plan and the user is prompted instep 806 that the action failed and/or that the snapshot is from themaster plan, and the process then returns to FIG. 4.

If the value field of the higher level relationship contains a GUID(step 803), herein called a hlr-GUID, there is a higher levelrelationship. it is checked, in step 807, from the packet relationshipinformation of the packet in the shared plan having a GUID correspondingto the current GUID in the tracking information, i.e. from the packetfound in step 802, whether or not the value field of the next packetindicates that a next packet exists in the shared plan.

If the value field of the next packet is associated with a GUID (step807), it indicates that the shared plan has one or more updates thatneed to be taken into account before loading from the higher level plan.Therefore the user is prompted in step 808 to perform “load” and onlyafter that to try “load from the higher level”. By loading first fromthe shared plan, and after that loading from the higher level sharedplan, facilitates maintaining plan hierarchy and change management, forexample. Then the process proceeds to FIG. 4. In another implementation,the steps of FIG. 5 may be performed in step 808 and then the processcontinues to step 809.

If the value field of next packet is not associated with a GUID (step807), it indicates that there are no updates in the shared plan thatneeds to be taken into account before loading from the higher levelplan. Therefore loading from the higher level plan is started in step809 by searching in the higher level shared plan for a packet having thehlr-GUID. In the illustrated example it is assumed that such a packet isfound. Then it is checked in step 810 from the packet relationshipinformation of the packet found in the higher level shared plan whetheror not the value field of the next packet indicates that a next packetexist. If the value field is associated with a GUID, the next packet(s)in the higher level shared plan is/are loaded in step 811, as long asthere are in the higher level shared plan next packets to be loaded. Inother words, the packet last loaded from the higher level shared plan isa packet whose value field of the next packet is not associated with aGUID. For example, if a user has taken a snapshot from packet C1 in FIG.1, packets A4 and A5 are loaded.

Then an update packet for the shared plan is formed in step 812. Thepacket relationship information of the update packet contains in thefield value of the previous packet GUID which is still indicated as thecurrent in the tracking information (and which was used in step 802),the next packet has no association or “none” or “no”, the GUID of thelast packet loaded in step 811 is added to the field value of the higherlevel relationship, and “load” is added to the value field of the higherlevel action. Further, a new GUID is obtained in step 812 and content isadded to the packet, the content containing at least changes caused bythe loaded higher level information.

Then the packet is saved in step 813 in the shared plan in the datarepository, and the packet relationship information of the packet foundin step 802 is updated so that the value field of next packet isassociated with the new GUID of the formed and saved packet. Thetracking information is updated in step 814 to have the new GUID of thepacket saved in step 813 in the shared plan as the value of the current,the higher level relationship is set to have the GUID of the packet lastloaded in step 811 from the higher level shared plan, and the lasthigher level action is set to load. Then the process returns to FIG. 4.

In another implementation, steps 811 to 814 are performed packet bypacket, for example first on packet A4 and then on packet A5 so thatthere will be two new packets in the shared plan C.

If in step 810 it is detected that no next packet exists, there are nonew packets to be loaded from the higher level plan, and the processreturns to FIG. 4.

It should be appreciated that after a packet has been loaded to thelocal copy, or after loading of packets ends, the packet(s) may undergoa change management/conflict handling procedure, for example the changemanagement based on the principle of causality and dualistic sequenceinformation described above. However that need not be described in moredetail here.

FIG. 9 illustrates an example of steps performed in response to “save tohigher level plan” action.

When the user has selected “save to higher level plan”, the GUIDs of thecurrent (c-GUID) and the higher level relationship (hl-GUID) areobtained in step 901 from the tracking information. Then the currentpacket is searched for from the shared plan in step 902. In theillustrated example, it is assumed that such a packet is found. Then itis checked in step 903 from the packet relationship information of thefound current packet whether or not the value field of the next packetindicates that a next packet exists.

If the value field of the next packet is associated with a GUID (step903), there are updates in the shared plan that have not been taken intoaccount and the user is prompted in step 904 to perform “load” before“save to higher level plan” can be performed. Then the process returnsto FIG. 4.

If the value field of the next packet is not associated with a GUID(step 903), a packet having an hl-GUID is searched for from the higherlevel shared plan in step 905. In the illustrated example, it is assumedthat such a packet is found. Then it is checked in step 906 from thepacket relationship information of the found higher level packet,whether or not the value field of the next packet indicates that a nextpacket exists.

If the value field of the next packet is associated with a GUID (step906), there are updates to the higher level plan in the shared data thathave not been taken into account and the user is prompted in step 907 toperform “load from higher level” before “save to higher level plan” canbe performed. Then the process returns to FIG. 4.

If the value field of the next packet in the higher level packet is alsonot associated with a GUID (step 906), there are no updates that need tobe taken into account. Then a new GUID is obtained and a new packet forthe higher level plan is formed in step 908, the packet containingmodifications made to the plan after the packet indicated by the valuefield of the higher level packet (so called “higher level packet”) wasformed, including loaded information and information that may have beenstored locally in a local packet formed later than the “higher levelpacket”, and/or saved in the shared plan later than the “higher levelpacket”. The packet relationship information of the packet formed instep 908 contains as the previous packet the GUID of the previous higherlevel packet (hl-GUID). Then the packet is saved in step 909 in thehigher level shared plan in the data repository and the packetrelationship information of the previous higher level packet is updatedin step 909 so that the value field of the next packet is associatedwith a GUID (new GUID) of the saved packet.

Then another new GUID (“another new GUID”) is obtained and a new packetfor the plan is formed in step 910, the packet containing modificationsmade to the shared plan after the packet indicated by the value field ofthe current packet (so called “current packet”) was formed, includingloaded information and information that may have been stored locally ina local packet formed later than the “current packet”. The packetrelationship information of the packet formed in step 910 contains asthe previous packet the GUID of the previous “current packet” (c-GUID),as a higher level relationship the GUID (new GUID) obtained in step 908for the packet formed in step 908 and as a higher level action “save”.Then the packet is saved in step 911 in the shared plan in the datarepository, and the packet relationship information of the previouspacket is updated in step 909 so that the value field of the next packetis associated with the GUID of the saved packet (another new GUID). Thenthe tracking information is updated in step 912 correspondingly, i.e.the value field of the current is set to “another new GUID”, the valuefield of the higher level relationship is set to “new GUID”, and thelast higher level action is set to “save”. Then the process returns toFIG. 4.

Although in the above steps 909 and 911 are described as separate savingsteps, it should be appreciated that the steps are preferably but notnecessarily performed using the atomic transaction principles.

FIG. 10 illustrates an example of steps performed in response to “createnew” action.

When the user has selected “create new”, the user is prompted, in step1001, to provide plan data, such as a name for the plan and possibleadditional information, like the purpose of this version, and whether itis intended to be an alternative, and if yes, preferably informationidentifying another/other alternative plan(s). The plan data is receivedin step 1002 and a start packet for the plan is formed in step 1003. Forthe start packet a new GUID is obtained in step 1003, and also otherpacket relationship information is set. The packet relationshipinformation of the start packet contains in the value field of theprevious packet no information or “none”, the value field of the nextpacket has no association, the GUID of the selected packet used forsnapshot in step 401 in FIG. 4 is added to the field value of the higherlevel relationship, and no information or “none” is added to the valuefield of the higher level action.

Then the name of the plan is compared in step 1004 with the names in thehierarchy information of the shared model in the data repository tominimize a danger of confusion with several users sharing the model, orpart of the model. If the intended name is the same as a name alreadyused (step 1005), the user is prompted in step 1006 to input (enter) anew name. When the new name is received in step 1007, the processcontinues to step 1004 to compare the new name with the names in thehierarchy information.

When the name is not a previously used name, the start packet is savedin step 1008 to be a new shared plan in the shared model datarepository, and the hierarchy information of the shared model is updatedin step 1009 to contain required information on the new plan, such asthe name of this new plan, the name of the higher level plan of this newplan, adding this new plan as a new lower level plan to the higher levelplan, etc. In one implementation, the start packet comprises the planname. Further, tracking information is updated in step 1009 to have thenew GUID obtained in step 1003 for the start packet as the value of thecurrent, and the process returns to FIG. 4.

Although in the above it is assumed that the actions “save to higherlevel”, and “load from higher level” store the changes also in theshared plan below the shared higher level plan, it should be appreciatedthat instead of changes, a reference to a packet in the higher levelcontaining the changes is stored in the shared plan. Yet anotherpossibility is to store, in addition to the changes, also the full(prevailing) state of the shared model at the time of the storing. Thiscan be applied to any “save” or “load”, and an implementation may mixthese different possibilities.

It may be that the thus obtained hierarchy structure needs to bereorganized. FIGS. 11 to 13 disclose a different hierarchy organizingfunctionality the plan managing unit may be configured to perform. Inthe examples below, it is assumed that corresponding plans are loaded tothe working memory and have corresponding tracking information. Further,a packet is used as an example of a data item.

FIG. 11 illustrates a functionality in which a shared plan X is moveddownwards so that it will be below a shared plan Z having the samehigher level shared plan Y. For example, using the plans illustrated inFIG. 1, it may be that the plan B should be between the plan A and themaster plan M.

When it is detected that the shared plan X is to be moved downwardsbelow the shared plan Z with which the shared plan X has the same higherlevel shared plan Y, a last packet (i.e. the latest one stored in theshared plan X) containing in its packet relationship information in thevalue field of the higher relationship a GUID to the shared plan Y, i.e.Y-GUID, is searched for in step 1101 from the shared plan X. When thepacket is found (denoted herein X-GUID), it is checked in step 1102whether or not the higher level action is “load from higher level”. Inother words, it is checked whether or not the last higher level actionwas load. If not, the user is prompted in step 1103 that it is notpossible to change the hierarchy. The user may also be prompted in step1103 for the reason and/or provided with instructions as to whichaction(s) to perform so that changing the hierarchy will be possible.For example, the user may be prompted to perform “load from the plan Xto higher level” before the shared plan X can be moved downwards.

If the last performed higher level action was load (step 1102), the GUIDof the corresponding packet in the higher level shared plan Y, i.e.Y-GUID, is taken in step 1104 and a corresponding packet is searched forin step 1105 from the shared plan Z. When the packet (Z-GUID) is found,it is checked in step 1106 whether or not the packet contains as itshigher level action “saved to higher level”. If not, the processproceeds to step 1103 to prompt the user.

If the higher level action of the packet Z-GUID is “save to higherlevel” (step 1106), the change of hierarchy is possible since the packetsaved from the shared plan Z in the higher level shared plan Y is loadedto the shared plan X. Therefore in step 1107, the higher level hierarchyinformation of the packet in the shared plan X and found in step 1101,i.e. X-GUID, is associated with the packet (Z-GUID) found in step 1105in the shared plan Z. In other words, after step 1107, the higher levelrelationship information of X-GUID indicates Z-GUID instead of Y-GUIDbut the higher level action remains to be load, and the higher levelrelationship now refers to the shared Z plane and the hierarchyrelationship is changed.

Then a new packet is formed in step 1108 for the plan X. In other words,a new GUID is obtained and the packet relationship information is set.The packet formed in step 1108 may contain modifications made to thelocal copy of the plan X after the packet indicated by the value fieldof current (so called “current packet”) in the tracking information ofthe shared plan X was formed, including loaded information andinformation that may have been stored locally in a local packet formedlater than the “current packet”, if any such modifications exist. Thepacket relationship information of the packet formed in step 1108contains as the previous packet the GUID of the current in the trackinginformation, and the value field of the higher level relationship, thevalue field of the last higher level action and the value field of thenext packet has no association (or is left empty) and is set to be load.

Then the packet is saved in step 1109 in the shared plan X in the datarepository, including updating the packet relationship information ofthe previous packet in the shared plan X so that the value field of nextpacket is associated with the GUID of the formed and saved packet. It isassumed that the saving is not an inline processing procedure and thatno other user tries or succeeds to save a new plan between the sharedplans Z and X during the saving procedure of step 1109. The trackinginformation of the plan X is also updated in step 1110 to have the GUIDof the formed and saved packet as the value of the current, and thehierarchy information of the shared model is updated in step 1110 toreflect the amended situation. In other words, Y in plan X informationis replaced by Z, X is moved from a lower level of plan Y to a lowerlevel of plan Z.

FIG. 12 illustrates another exemplary functionality in which a hierarchylevel is deleted. Using the situation after FIG. 11 as an example, ifthe shared plan X which is below the shared plan Z which, in turn, isbelow the shared plan Y is to be moved so that the shared plan X is nolonger below the shared plan Z but the shared plan Y will be the higherlevel plan for the shared plans X and Z. For the sake of clarity, it isassumed that the hierarchy exists, i.e. the shared plans X and Z have atleast one packet having a GUID in the value field of higher levelrelationship in the packet relationship information. If not, the requestis rejected. The hierarchy change is allowable if the last performedhigher level action in the shared plan X is “load from higher level”,and the loaded packet was saved from the shared plan Z in the sharedplan Y. However, there may be other higher level actions performed inthe shared plan Z after that.

When it is detected that the hierarchy level of the shared plan X is tobe moved upwards, a last packet (i.e. the latest one stored in theshared plan X) containing in its packet relationship information in thevalue field of the higher relationship a GUID to the shared plan Z, i.e.Z-GUID, is searched for in step 1201 from the shared plan X. When thepacket is found (denoted herein X-GUID), it is checked in step 1202,whether or not the higher level action is “load from higher level”. Ifnot, the user is prompted in step 1203 that it is not possible to changethe hierarchy. The user may also be prompted in step 1203 for the reasonand/or provided with instructions as to which action(s) to perform sothat changing the hierarchy will be possible.

If the last higher level action is “load from higher level”, the GUID ofthe corresponding packet in the higher level shared plan Z, i.e. Z-GUID,is taken in step 1204 and a corresponding packet is searched for in step1205 from the shared plan Z. When the packet is found, it is checked instep 1206 whether or not the packet contains as its higher level action“save to higher level”. If not, the process proceeds to step 1203 toprompt the user.

If the higher level action of the packet Z-GUID is “save to higherlevel” (step 1206), the change of the hierarchy is possible. Thereforein step 1207, the higher level hierarchy information of the packet inthe shared plan X and found in step 1201, i.e. X-GUID, is associatedwith the same packet (Y-GUID) in the higher level plan Y as that wheretothe packet Z-GUID refers. In other words, after the step 1207, thehigher level relationship information of X-GUID indicates Y-GUID insteadof Z-GUID but the higher level action remains to be “load”, and thehigher level relationship now refers to the shared Y plane and thehierarchy relationship is changed.

Then a new packet is formed in step 1208 for plan X. In other words, anew GUID is obtained and the packet relationship information is set. Thepacket formed in step 1208 may contain modifications made to the localcopy of plan X after the packet indicated by the value field of current(so called “current packet”) was formed, including loaded informationand information that may have been stored locally in a local packetformed later than the “current packet”, if any such modifications exist.The packet relationship information of the packet formed in step 1208contains as the previous packet the GUID of the current in the trackinginformation for the plan X, but the higher level relationship, the lasthigher level action and the next packet has no association (or is leftempty).

Then the packet is saved in step 1209 in the shared plan X in the datarepository, including updating the packet relationship information ofthe previous packet in the shared plan X so that the value field of thenext packet is associated with the GUID of the formed and saved packet.It is assumed that the saving is not an inline processing procedure andthat no other user tries or succeeds to save a new plan between plans Xand Y during the saving procedure of step 1209. The tracking informationof plan X is updated in step 1210 to have the GUID of the formed andsaved packet as the value of the current, and the hierarchy informationof the shared model is updated in step 1210 to reflect the amendedsituation. In other words, Z in plan X information is replaced by Y, Xis moved from a lower level of plan Z to a lower level of plan Y.

FIG. 13 illustrates a functionality in which a plan contains a packetcomprising a severe fault, like something destroying the plan. Forexample, using the plans illustrated in FIG. 1, it may be that a packetA4 is the one that is not wanted in the shared plan. In other words, itis an unwanted packet, and it is used as an example of such an unwantedpacket below.

When an unwanted packet is detected, a “turn tail” action may betriggered. The “turn tail” action is preferably but not necessarily aninline operation requiring some kind of locking of the shared plan whosetail is to be turned. If no hierarchy information is separatelymaintained, this kind of hierarchy changes may be maintained using aside-channel queue to speed up detection of the changes, as comparedwith a solution in which the hierarchy is determined only using thepacket relationship information.

In response to the “turn tail” action, packet relationship informationof the unwanted packet (A4) and all next (subsequent) packets (A5) isobtained in step 1301. Then it is checked in step 1302 whether any ofthe packets has “save” in the value field of the higher level action. Ifany of them contains “save”, no “turn tail” action can be performed, andthe user is prompted in step 1303 correspondingly.

If no higher level save action has been performed in the unwanted packetor after it (step 1302), packet relationship information of a packet(A3) previous to the unwanted packet is obtained in step 1304. Then instep 1305 plan data is generated automatically, the plan data containingas a plan name “tail x”, x illustrating consecutive numbering of tails,and it may contain as an additional information “faulty data”.

Further, a start packet for the plan is created in step 1306. The packetrelationship information of the start packet contains in the field valueof the previous packet no information or “none”, the field value of thenext packet is associated with the GUID of the unwanted packet (A4), theGUID of the previous packet (A3) is added to the field value of thehigher level relationship, and the value field of the higher levelaction is associated with information indicating that this plan is notto be used (i.e. none should use this plan). Information indicating thatactions “load from the higher level” and “save to the higher level” arenot allowed for this plan, and if one of the actions is tried, an erroris returned, may be provided as side-channel information. A new GUID isobtained in step 1306 for the start packet but no actual content isadded to the start packet even in implementations in which the startpacket may contain actual content.

Then the packet is saved in step 1307 to be a new shared plan in thedata repository. The packet relationship information of the unwantedpacket (A4) is updated in step 1308 so that the value field of theprevious packet is set to be the new GUID and the packet relationship ofthe previous packet (A3) is updated in step 1308 by emptying/deletingthe association of the value field of the next packet, or setting it to“none”. After that the packet A3 would be the last one in the plan A,and the packets A4 and A5 would have been moved to another plan (linkedto the plan A via an empty packet (identified by the new GUID)). Thehierarchy information of the shared model is updated in step 1309 tocontain required information on the new plan, such as the name of thisnew plan, the name of the higher level plan of this new plan, addingthis new plan as a new lower level plan to the higher level plan, etc.

In another implementation, the “turn tail” process also compriseschecking whether the unwanted packet belongs to a plan that is a higherlevel plan for one or more other plans, and if it is, it is checkedwhether the unwanted packet has been loaded to the one or more plans,and if it has been loaded, “turn tail” is performed on the packetwhereto the unwanted packet was loaded, the lower level packet becomingan unwanted packet of that level. The process is preferably performedrecursively downwards in the hierarchy. An advantage of this is thatfaulty data is no longer used nor usable in the model.

Although not described above, the (packet) relationship information, orthe packet itself separately from the relationship information, maycontain flags for indicating whether the shared plan the packet belongsto is closed by the packet, or should be treated as a deleted one, forexample. The flag values may then be used by the actions described aboveto determine whether or not to allow a snapshot, a load and/or a savefrom/in the plan, for example.

FIG. 14 illustrates a functionality according to an exemplary embodimentin which a database management system, or corresponding system, isconfigured to monitor the “save” action and provide a fallback solutionwhen the “save” action fails. The database management system maycomprise for this purpose a save monitoring unit, that may beimplemented by hardware, firmware, software, or combinations thereof.For firmware or software, implementation can be through units/modules(e.g. procedures, functions, algorithms and so on) that perform thefunctions described herein.

Referring to FIG. 14, when the save monitoring unit detects in step 1401that a client tries to save in a plan A but the save fails, for examplebecause another client has locked the plan A because the other client iscurrently performing the save action. Another example may be that,referring to the situations described above with FIG. 6, the savemonitoring unit detects that the packet indicated as current is searchedfor and the value field of the packet indicated as current indicatesthat a next packet exits, and the save monitoring unit is configured todetermine whether or not loading packets is possible and if notpossible, to determine that the save fails. Yet another example is thatthe save monitoring unit detects that after the load, while the packetis formed in step 607, a new packet is stored in the shared plan (i.e.answer to question of step 608) would be yes, the save monitoring unitmay decide to treat the situation as a failed save. This is especiallyuseful if the client is not configured to perform the check of step 608.(If the client is configured to perform the check of step 608, and thesave monitoring unit decide to treat the situation as a failed save, itmay “fool” the client by indicating that no next data item exists, i.e.by responding to a request asking whether or not during the time thepacket was formed after the last loaded packet, one or more packets hasbeen saved to the plan, that the last loaded packet is the last one inthe plan even though there are one or more next packets.)

In response to the failed save, the save monitoring unit generates instep 1402 plan data for a new plan and creates in step 1403 a startpacket for the new temporary plan. The plan data may correspond to theplan data described with FIG. 6. After that the start packet and thedata item(s) the client tries to save in the plan A are saved in the newplan. In the example, the client is also informed in step 1405 thatinstead of the “save”, “save as new” was performed. The hierarchyinformation is also updated in step 1406. Now the data is usable to theclient and other clients as any other shared plan in the shared memory.

This way all work can be saved to the shared memory as a new plan, whichcan later be saved to the original plan by using “load higher” and then“save in higher” actions. This will result in changes being merged intothe original plan, and adding a new packet in the created new plan, thenew packet indicating that “save in higher” has happened, as isdescribed with FIG. 9. Depending on an implementation, any client and/orthe save monitoring unit or only the client that tried to perform “saveaction” but instead ended up to perform “save as new” action may performthe “save to higher” action.

An advantage provided by the above described functionality of the savemonitoring unit, or corresponding functionality, is that the user isable to perform “save” in the shared memory at the time the userintended to save it.

In a still further embodiment, the client may be configured in the savemode only to form the packet, save the packet in the plan and update thetracking information, the save monitoring unit is configured to eithersave the packet as new plan or perform the loading, conflict handling,and forming a further packet which then will be saved to the sharedplan.

It should appreciated that the client may be configured to perform themonitoring illustrated in FIG. 4, and one or more of the functionalitiesillustrated in FIGS. 5 to 13 are performed at the server, for example bythe save monitoring unit.

The steps shown in FIGS. 4 to 14 are in no absolute chronological order,and some of the steps may be performed simultaneously or in an orderdifferent from the given one, and steps in one figure may be performedsimultaneously or overlappingly with steps in another figure. Otherfunctions can also be executed between the steps or within the steps.Some of the steps or part of the steps can also be left out. For examplesteps 703 to 706 in FIG. 7, or steps 1004 to 1007 in FIG. 10, may beleft out. The steps, and steps in different Figures, can also be freelycombined or divided into several parts.

It will be obvious to a person skilled in the art that as technologyadvances, the inventive concept can be implemented in various ways. Theinvention and its embodiments are not limited to the examples describedabove but may vary within the scope of the claims.

The invention claimed is:
 1. A method comprising: maintaining a shareddata in a shared model, the shared data comprising a plurality of sharedplans where each shared plan comprises one or more data items in asequential order, the plurality of shared plans comprising a master planand at least one parallel plan and a plurality of alternative plans,wherein at least one of the plurality of alternative plans are capableof being selected to be deleted upon storing of the shared model; andwherein each data item contains relationship information comprising anidentifier, previous data item information, next data item information,and higher level relationship information; associating a first data itemstored in a shared plan selected from the group consisting of the masterplan, the at least one parallel plan, and the plurality of alternativeplans, with the relationship information indicating: whether or not thefirst data item has a previous data item in the shared plan, whether ornot the first data item is associated with a next data item in theshared plan, and whether or not the first data item has a relationshipto a second data item in a higher level plan, information representingan existing relationship indicating that the first data item is astarting data item for the shared plan, and information representing amissing relationship indicating that the first data item is one of theone or more data items for the shared plan, wherein the plurality ofdata items further includes a third data item that is in a relationshipwith both the second data item in the higher level plan and another dataitem in the plurality of data items; detecting that the first data itemis unwanted; obtaining the relationship information of the first dataitem and relationship information of data items subsequent to the firstdata item; determining that none of the data items subsequent to thefirst data item are to be saved; creating a new shared plan comprising astart packet, the start packet having no previous data item informationbut having next data information that indicates the next data item isthe first data item; and moving the first data item and the data itemssubsequent to the first data item to the new shared plan, the data itemssubsequent to the first data item being positioned subsequent to thefirst data item in the new shared plan.
 2. A method as claimed in claim1, further comprising: forming a hierarchical structure using therelationship information so that if there is a previous data item, thefirst data item is placed after the previous data item, if there is anext data item, the first data item is placed before the next data itemand if the first data item has the relationship, linking the first dataitem and the second data item in the higher level plan.
 3. A method asclaimed in claim 1, further comprising: obtaining a working copy of theshared plan by taking a snapshot from the first data item; and creatingtracking information for the plan, the tracking information indicatingthe first data item as a current data item.
 4. A method as claimed inclaim 3, further comprising performing a primary load by loading to theworking copy from the shared model at least the previous data item ofthe current data item, if there is a previous data item.
 5. A method asclaimed in claim 4, further comprising: receiving a load instruction asa user input; searching for the first data item indicated as the currentdata item from the shared model; finding the first data item; checkingwhether the found data item is associated with a next data item; loadingthe associated data item to the working copy; checking whether theassociated data item is associated with a next data item; and repeatingthe loading and checking of associated data items until there is anassociated data item that is not associated with a next data item.
 6. Amethod as claimed in claim 4, further comprising: receiving a saveinstruction as a user input; searching for the first data item indicatedas the current data item from the shared model; finding the first dataitem; checking whether the found data item is associated with a nextdata item; if the found data item is associated with a next data item,loading the associated data item to the working copy, checking whetherthe associated data item is associated with a next data item; andrepeating the loading and checking of associated data items until thereis an associated data item that is not associated with a next data item;forming a further data item to be stored in the shared plan; indicatingthe last loaded data item as a previous data item for the further dataitem; storing the further data item with the indication of the previousdata item in a shared memory; associating the last loaded data item withinformation identifying the further data item as a next data item; andupdating the tracking information to indicate the further data item asthe current data item.
 7. A method as claimed in claim 4, furthercomprising: receiving an instruction to load from a higher level sharedplan as a user input; searching for the third data item having arelationship to a higher level data item in the higher level plan fromthe shared plan; finding the third data item; searching for the higherlevel data item indicated in the relationship information of the thirddata item; finding the higher level data item; checking whether thefound higher level data item is associated with a next data item;loading the associated next data item from the higher level plan to theworking copy; checking whether the associated next data item isassociated with a next data item; and repeating the loading from thehigher level plan to the working copy until there is an associated dataitem that is not associated with a next data item.
 8. A method asclaimed in claim 7, further comprising: checking whether the found dataitem is associated with a next data item; and searching for the higherlevel data item only and performing subsequent steps if the found dataitem is not associated with a next data item.
 9. A method as claimed inclaim 8, further comprising, if the found data item is associated with anext data item: loading the associated data item to the working copy;checking whether the associated data item is associated with a next dataitem; repeating the loading and checking of associated data items untilthere is an associated data item that is not associated with a next dataitem, and only after that searching for the higher level data item andperforming subsequent steps.
 10. A method as claimed in claim 4, furthercomprising: receiving an instruction to save in a higher level sharedplan as a user input; searching for the third data item having arelationship to a higher level data item in the higher level plan fromthe shared plan in the shared model; finding the third data item;searching for the higher level data item indicated in the relationshipinformation of the third data item from the shared model; finding thehigher level data item; checking whether or not the found higher leveldata item is associated with a next data item; if not, forming a furtherhigher level data item to be stored to the higher level shared plan;indicating the found higher level data item as a previous data item forthe further data item; storing the further higher level data item withthe indication of the previous data item in the shared memory; andassociating the found higher level data item with informationidentifying the further data item as a next data item.
 11. A method asclaimed in claim 10, further comprising in response to storing thefurther higher level data item: forming a further data item; indicatingin the relationship information of the further data item the furtherhigher level data item as the relationship in the higher level plan; andstoring the further data item to the shared plan.
 12. A method asclaimed in claim 1, further comprising: receiving as a user input aninstruction to move a first shared plan having a second shared plan as ahigher level plan below a third shared plan having the second sharedplan as the higher level plan; checking whether or not there is in thesecond shared plan a data item that is stored from the third plan andloaded to the first plan as a last performed higher level action; and ifthere is, moving the first shared plan below the third plan byassociating in the first shared plan the higher level relationshipinformation of a data item whereto the loading was performed with a dataitem in the third shared plan as the higher level relationship, the dataitem in the third plan indicating in its higher level relationship thedata item stored in the second shared plan.
 13. A method as claimed inclaim 1, further comprising: receiving as a user input an instruction tomove a first shared plan having a second shared plan as a higher levelplan below a third shared plan which is as the higher level plan of thesecond shared plan; checking whether or not the last higher levelrelationship of the first shared plan indicates loading from the secondshared plan; if yes, checking whether or not a data item in the secondshared plan and indicated by the higher level relationship of the firstshared plan has been stored in the third shared plan; if yes, moving thefirst shared plan below the third plan by associating in the firstshared plan the higher level relationship information of a data itemwhereto the loading was performed with a data item in the third planindicated by the relationship information of the data item in the secondplan.
 14. A method as claimed in claim 1, further comprising: receivingas a user input an instruction to make a plan unusable from a data item;checking whether or not storing in a higher level plan has beenperformed in the data item or after the data item; if not, removing theassociation indicating the data item as a next data item.
 15. A methodas claimed in claim 4, further comprising: receiving a save instructionas a user input; searching for the first data item indicated as thecurrent data item from the shared model; finding the first data item;checking whether the first data item is associated with a next dataitem; if the first data item is associated with a next data item:forming a starting data item for a new plan and a second data item, thestarting data having as relationship information no previous data item,the second data item as the next data item, and a relationship to thefound data item indicated as the current data item in the plan the saveinstruction was targeted to, the plan being a higher level plan for thenew plan, the second data item having as relationship information thestarting data item as the previous data item and no next data item andno relationship to a data item in the higher level plan; and storing thestarting data item and the second data item in the shared model as thenew plan.
 16. A method comprising: maintaining in a shared memory ashared model that comprises a hierarchical plan structure, a highestplan comprising one or more data items, each of the data itemsindicating that it does not have a relationship to a data item in ahigher level plan, the highest plan forming the final plan for themodel, and one or more other shared plans, each other plan comprisingone or more data items, at least one of the data items having arelationship to a data item in the highest plan or in a higher levelplan between the other plan and the highest plan in the hierarchicalplan structure, the hierarchical plan structure being formed by means ofthe relationships of the data items, each of the one or more other plansbeing a parallel plan intended to be saved in the highest plan or in thehigher level plan when it is ready for storing, or alternative planssuch that one of the alternative plans is selected to be saved in thehighest plan or in the higher level plan, and other alternative plansthat are not selected to be saved are capable of being selected to bedeleted when the shared model is stored, wherein each data item containsrelationship information comprising an identifier, previous data iteminformation, next data item information, and higher level relationshipinformation; forming a first data item to be added to a first plan ofthe one or more other shared plans; associating the first data itemstored in a shared plan selected from the group consisting of the masterplan, the at least one parallel plan, and the plurality of alternativeplans with information identifying a previous data item in the sharedplan; storing the first data item in the shared model; associating theprevious data item with information identifying the first data item as anext data item, such that the first data item and the previous data itemare in a sequential order in the first plan, wherein at least one dataitem in the first plan is in a relationship with both a data item in thehigher level plan and another data item in the first plan; detectingthat the first data item is unwanted; obtaining the relationshipinformation of the first data item and relationship information of dataitems subsequent to the first data item; determining that none of therelationship information of the data items subsequent to the first dataitem are to be saved; creating a new shared plan comprising a startpacket, the start packet having no previous data item information buthaving next data information that indicates the next data item is thefirst data item; and moving the first data item and the data itemssubsequent to the first data item to the new shared plan, the data itemssubsequent to the first data item being positioned subsequent to thefirst data item in the new shared plan.
 17. A method comprising:maintaining in a shared memory a shared model comprising at least afirst plan for the shared model, the first plan comprising at least afirst data item; forming a second data item for a second shared plan tobe added to the shared model below the first shared plan, the secondplan being parallel to the first plan or alternative to the first plan,the first plan forming part of the second plan up to and including thefirst data item, the second data item being a starting data item of thesecond plan, the second plan configured to include a third data item tobe added to the second shared plan and in a sequential order to thesecond data item, wherein the second data item is in a relationship withboth the first data item and the third data item, and wherein the firstplan or second plan is capable of being selected to be deleted uponstoring of the shared model when the second plan is alternative to thefirst plan, and wherein each of the first data item and the second dataitem contains relationship information comprising an identifier,previous data item information, next data item information, and higherlevel relationship information; associating the second data item withhigher level relationship information by identifying the first data itemin the first shared plan and with information indicating whether thesecond plan is parallel or alternative; storing the second data item inthe shared memory; detecting that the second data item is unwanted;obtaining the relationship information of the second data item andrelationship information of the third data item; determining that thethird data item is not to be saved; creating a new shared plancomprising a start packet, the start packet having no previous data iteminformation but having next data information that indicates the nextdata item is the second data item; and moving the second data item andthe third data item to the new shared plan, the third data item beingpositioned subsequent to the second data item in the new shared plan.18. A method as claimed in claim 17, further comprising: forming thethird data item to be added to the second shared plan; associating thethird data item with information identifying the second data item as aprevious data item in the second shared plan; storing the third dataitem in the shared model; and associating the second data item withinformation identifying the third data item as a data item that issubsequent to the second data item such that the second data item andthe third data item are in the second shared plan and in a sequentialorder.
 19. A method as claimed in claim 17, wherein the shared model isfor building information modelling in a multiuser environment.
 20. Amethod as claimed in claim 19, wherein the shared model comprises ahierarchical plan structure that comprises a highest plan comprising oneor more data items, each of the data items indicating that it does nothave a relationship to a data item in a plan that is at a higher level;and one or more other plans, each other plan comprising one or more dataitems, at least one of the data items having a relationship to a dataitem in the highest plan or in a higher level plan between the otherplan and the highest plan in the hierarchical plan structure, thehierarchical plan structure being formed by means of the relationshipsof the data items.
 21. An apparatus comprising at least one processor;and at least one memory including computer program code; the at leastone memory and the computer program code being configured to, with theat least one processor, cause the apparatus at least to: maintain, in ashared model a shared data accessible by a user via a user apparatus,the shared data comprising a plurality of shared plans where each sharedplan comprises one or more data items in a sequential order, theplurality of shared plans comprising a master plan and at least oneparallel plan and a plurality of alternative plans, wherein at least oneof the plurality of alternative plans are capable of being selected tobe deleted upon storing of the shared model; and wherein each data itemcontains relationship information comprising an identifier, previousdata item information, next data item information, and higher levelrelationship information; associate a first data item stored in a sharedplan selected from the group consisting of the master plan, the at leastone parallel plan, and the plurality of alternative plans withrelationship information indicating whether or not the first data itemhas a previous data item in the shared plan, whether or not the firstdata item is associated with a next data item in the shared plan, andwhether or not the first data item has a relationship to a second dataitem in a higher level plan, information representing an existingrelationship indicating that the first data item is a starting data itemfor the shared plan, and information representing a missing relationshipindicating that the first data item is one of the one or more data itemsfor the shared plan, wherein the plurality of data items furtherincludes a third data item that is in a relationship with both thesecond data item in the higher level plan and another data item in theplurality of data items; detect that the first data item is unwanted;obtain the relationship information of the first data item andrelationship information of data items subsequent to the first dataitem; determine that none of the data items subsequent to the first dataitem are to be saved; create a new shared plan comprising a startpacket, the start packet having no previous data item information buthaving next data information that indicates the next data item is thefirst data item; and move the first data item and the data itemssubsequent to the first data item to the new shared plan, the data itemssubsequent to the first data item being positioned subsequent to thefirst data item in the new shared plan.
 22. An apparatus comprising atleast one interface configured to provide access to a shared memory; atleast one processor; and at least one memory including computer programcode; the at least one memory and the computer program code beingconfigured to, with the at least one processor, cause the apparatus atleast to load from the shared memory comprising a shared modelcomprising at least a first plan for the shared model, the first plancomprising at least a first data item at least information on the firstdata item; form a second data item for a second shared plan to be addedto the shared model below the first shared plan, the second plan beingparallel to the first plan or alternative to the first plan, the firstplan forming part of the second plan up to and including the first dataitem, the second data item being a starting data item of the secondplan, the second plan configured to include a third data item to beadded to the second shared plan and in a sequential order to the seconddata item, wherein the second data item is in a relationship with boththe first data item and the third data item, and wherein the first planor second plan is capable of being selected to be deleted upon storingof the shared model when the second plan is alternative to the firstplan, and wherein each of the first data item and the second data itemcontains relationship information comprising an identifier, previousdata item information, next data item information, and higher levelrelationship information; associate the second data item with higherlevel relation information by identifying the first data item in thefirst shared plan and with information indicating whether the secondplan is parallel or alternative; store the second data item in theshared memory; detect that the second data item is unwanted; obtain therelationship information of the second data item and relationshipinformation of the third data item; determine that the third data itemis not to be saved; create a new shared plan comprising a start packet,the start packet having no previous data item information but havingnext data information that indicates the next data item is the seconddata item; and move the second data item and the third data item to thenew shared plan, the third data item being positioned subsequent to thesecond data item in the new shared plan.
 23. A non-transitorycomputer-readable storage medium having computer-readable instructionsexecutable by a computer such that, when executing said instructions,said computer will: maintain, in a shared model a shared data accessibleby a user via a user apparatus, the shared data comprising a pluralityof shared plans where each shared plan comprises one or more data itemsin a sequential order, the plurality of shared plans comprising a masterplan and at least one parallel plan and a plurality of alternativeplans, wherein at least one of the plurality of alternative plans arecapable of being selected to be deleted upon storing of the sharedmodel; and wherein each data item contains relationship informationcomprising an identifier, previous data item information, next data iteminformation, and higher level relationship information; associate afirst data item stored in a shared plan selected from the groupconsisting of the master plan, the at least one parallel plan, and theplurality of alternative plans with relationship information indicating:whether or not the first data item has a previous data item in theshared plan, whether or not the first data item is associated with anext data item in the first shared plan, and whether or not the firstdata item has a relationship to a second data item in a higher levelplan, information representing an existing relationship indicating thatthe first data item is a starting data item for the first shared plan,and information representing a missing relationship indicating that thefirst data item is one of the one or more data items for the firstshared plan, wherein the plurality of data items in the sequential orderfurther includes a third data item that is in a relationship with thesecond data item in the higher level plan; detecting that the first dataitem is unwanted; obtaining the relationship information of the firstdata item and relationship information of data items subsequent to thefirst data item; determining that none of the data items subsequent tothe first data item are to be saved; creating a new shared plancomprising a start packet, the start packet having no previous data iteminformation but having next data information that indicates the nextdata item is the first data item; and moving the first data item and thedata items subsequent to the first data item to the new shared plan, thedata items subsequent to the first data item being positioned subsequentto the first data item in the new shared plan.
 24. A system comprisingat least one or more first computing apparatuses, each comprising a datastorage for storing a shared model comprising a hierarchical planstructure that comprises a highest plan comprising one or more dataitems, each of the data items in the highest plan indicating that itdoes not have a relationship to a data item in a higher level plan, thehighest plan forming the final plan for the model, and one or more othershared plans, each other plan comprising one or more data items, atleast one of the data items in a shared plan having a relationship to adata item in the highest plan or in a higher level plan between theother plan and the highest plan in the hierarchical plan structure, thehierarchical plan structure being formed by means of the relationshipsof the data items, each of the one or more other plans being a parallelplan intended to be saved in the highest plan or in the higher levelplan when it is ready for storing, or alternative plans such that, oneof the alternative plans is selected to be saved in the highest plan orin the higher level plan, and other alternative plans that are notselected to be saved are capable of being selected to be deleted whenthe shared model is stored, wherein each data item contains relationshipinformation comprising an identifier, previous data item information,next data item information, and higher level relationship information;one or more second computing apparatuses, a second apparatus beingconfigured to have access to the data storage and configured to form afirst data item to be added to one of the one or more shared plans,associate the first data item stored in a shared plan selected from thegroup consisting of the master plan, the at least one parallel plan, andthe plurality of alternative plans with information identifying aprevious data item in the shared plan, store the first data item in theshared model, and associate the previous data item with informationidentifying the first data item as a next data item, such that the firstdata item and the previous data item are in a sequential order in theshared plan, wherein at least one data item in the shared plan is in arelationship with both a data item in the higher level plan and anotherdata item in the shared plan; detecting that the first data item isunwanted; obtaining relationship information of the first data item andrelationship information of data items subsequent to the first dataitem; determining that none of the data items subsequent to the firstdata item are to be saved; creating a new shared plan comprising a startpacket, the start packet having no previous data item information buthaving next data information that indicates the next data item is thefirst data item; and moving the first data item and the data itemssubsequent to the first data item to the new shared plan, the data itemssubsequent to the first data item being positioned subsequent to thefirst data item in the new shared plan.